Avalanche photodiode

Abstract

An APD is provided with a semi-insulating substrate, a first mesa having a first laminate constitution in which a p-type electrode layer, a p-type light absorbing layer, a light absorbing layer with a low impurity concentration, a band gap inclined layer, a p-type electric field control layer, an avalanche multiplier layer, an n-type electric field control layer, and an electron transit layer with a low impurity concentration are stacked in this order on a surface of the semi-insulating substrate, a second mesa having an outer circumference provided inside an outer circumference of the first mesa as viewed from the laminating direction and having a second laminate constitution in which an n-type electrode buffer layer and an n-type electrode layer are stacked in this order on a surface on the electron transit layer side of the first mesa, and in the APD, a total donor concentration of the n-type electric field control layer is lower than a total acceptor concentration of the p-type electric field control layer in a range of 2×1011 to 1×1012 / cm2.

Description

BACKGROUND[0001]1. Field of the Disclosure[0002]The present disclosure relates to a device structure of an avalanche photodiode.[0003]2. Discussion of the Background Art[0004]An avalanche multiplier photodiode (avalanche photodiode: APD) as a highly-sensitive light receiving device has been widely introduced in, for example, an optical communication system using a photocarrier in a long wavelength range (1.5 micron band). A typical APD device operated in the long wavelength range is of a hole-injection type in which InP is an avalanche multiplier layer and usually has a structure in which an avalanche multiplier region is specified by a pn junction formed by Zn thermal diffusion to InP and a guard ring is disposed around the junction surface.[0005]Meanwhile, it is assumed that in terms of rapidity and avalanche excess noise characteristics, an electron-injection type APD in which InAlAs is an avalanche multiplier layer is more advantageous than the hole-injection type APD in which I...

AI Technical Summary

Benefits of technology

The present disclosure provides an avalanche photodiode (APD) that can reduce dark current and edge breakdown, which are caused by mesa surface and electrode layer shape. The APD uses a specific electrode layer configuration and a relationship between donor and acceptor concentrations to prevent depletion and reduce dark current. Additionally, the APD has a donor concentration in the electrode buffer layer within a certain range to suppress tunnel current and avalanche current. The APD also has a reduced concentration of edge electric field and a reduced occurrence of edge breakdown and tunnel current. Overall, the present disclosure provides an APD that can effectively reduce dark current and edge breakdown.

Problems solved by technology

However, in an element manufacturing technical standpoint, a so-called “guard ring technique” for suppressing edge breakdown around a junction does not reach completeness in the hole-injection type.

One reason for this is that it is difficult to form an “ion-injection type guard ring structure” usually used in the hole-injection type.

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